1. Field of the Invention
This invention related to a method of stabilizing clayey geological formations by treatment with a quaternized amine oligomer.
2. Description of the Prior Art
When geological formations containing water swelling clays come in contact with water, particularly fresh water, clays in the formations may swell, disperse with attendant loss of permeability and/or mechanical strength, or otherwise interfere with recovery of petroleum or other minerals from the formations. Clayey formations are often impermeable or have low permeability or lose part or all of their permeability on contact of the clays with water or water base systems such as injection fluids, drilling muds, stimulation fluids and gels.
Clays in formations can reduce permeability by swelling or migrating to form bridges or blockages in formation pores or screens used in well completions. Swelling and migration occur when aqueous fluids used in oil recovery come in contact with the clays.
Clays can also cause trouble in areas other than permeability reduction. When they are a component in shales, sandstones, or other formations, contact with a foreign water or at times with any water can cause the formation to lose strength or even disintegrate. This is a problem in building foundations, road beds, drilling wells and any situation where the formation strength is important.
There have been numerous attempts to control the ill effects of water on clay and/or other fines. These have been principally in the oil industry. One idea is to convert the clay from the swelling sodium form (or the more rare swelling lithium form) to another cation form which is less sensitive.
Example cations that form relatively non-swelling clays are potassium, calcium, ammonium and hydrogen ions. When a solution of these cations, mixed or individually, flows past a clay mineral, they readily replace the sodium ion and the clay is transformed to a relatively non-swelling form. The use of acid, potassium, calcium, or ammonium ions to exchange for sodium ion has been successful in preventing damage to formations susceptible to plugging or disintegrating due to clays in their compositions.
However, the exchanging of other ions for sodium on clay is only a temporary remedy. When a well is produced, the presence of sodium ion in the formation water will enable sodium ion to counter replace hydrogen, potassium, ammonium or calcium ion quickly. As a result, the clay is returned to the swelling or dispersible form, ready to cause damage should a foreign water be introduced.
The prior art and conventional features useful with this invention are described in references cited and/or discussed herein. Each reference cited or discussed herein is incorporated herein by reference to any extent deemed necessary for any purpose.
U.S. Pat. No. 2,761,843--Brown, describes a process for preventing or reducing permeability loss in clay containing formations by treating the clay body with substituted ammonium ions derived from certain basic nitrogen compounds.
U.S. Pat. No. 3,349,032--Krieg, describes a process for preventing, inhibiting or reducing "clay blocking" or plugging of oil producing clayey formations during oil recovery by adding a polyquaternary amine.
U.S. Pat. No. 3,500,925--Beiswanger et al, describes a process for improving flow rate of injection water through oil producing formations during oil recovery by adding a water soluble polymer, of a N-vinyl lactam and a water soluble salt.
U.S. Pat. No. 4,158,521--Anderson et al, describes treating with a solution of a reaction product of dimethylamine and epichlorohydrin to stabilize clay containing formations in oil and gas producing boreholes after these formations are penetrated.
U.S. Pat. Nos. 4,336,071, 4,366,072, 4,366,073, 4,366,074, 4,462,718 and 4,374,739--McLaughlin et al, describes methods of preventing or reducing swelling, migrating or dispersing of clay in an oil producing formation by treating the clay with an organic polycationic polymer dissolved in a carrier to stabilize the clay against dispersion or expansion by water.
U.S. Pat. No. 4,505,833--Lipowski et al, describes a process for treating clayey formations using a quaternized oligomer which is the reaction product of a polyamine having a primary amino group and a tertiary amino group with a difunctional reactant to form a precondensate monomer which then is chain extended and quaternized by reaction with a dihalogenated hydrocarbon ether.